1. Field of the Invention
The present invention relates to an induction heating apparatus formed with slots on an interior portion thereof to assist with conduction of heat away from a central portion thereof.
2. Related Art
Induction sealing units for hermetically sealing a container with a foil sheet are typically included in conveyor systems for high volume applications. These systems usually have a flat or tunnel sealing heads mounted above a conveyor which carries a plurality of containers to be sealed into proximity with the sealing head.
The containers to be sealed are preconditioned to include a wax compound disposed between a foil sheet and the opening of the container. Usually, the foil sheet and wax compound are held in place by a screw-on or snap-on cap as is known in the art. Sometimes the wax compound is omitted and the foil sheet rests against a plastic material which forms the lip of the container.
Once the preconditioned container is brought within a predetermined distance from the sealing head, a coil within the sealing head produces an electromagnetic field near the foil sheet (or liner) which is disposed within the cap. The electromagnetic flux produced by the field causes the current to flow in the foil liner which causes the foil to heat and melt the wax compound (or the lip of the container). The molten wax (or plastic) adheres to both the foil liner and the opening of the container and, when the wax (or plastic) cools, an hermetic seal is produced. The downward force supplied by the cap ensures a proper bond between the foil liner and the opening of the container.
Typically, power supplies which include solid state switching circuits generate high frequency currents for delivery to the coil within the sealing head to produce the requisite electromagnetic field necessary to heat the foil liner. In addition, the coil in the sealing head is disposed around dense ferrite materials to channel the electromagnetic field and direct the field flux towards the foil liner for improved performance. Generally, the power supplies deliver approximately 2-4 kilowatts of power to the sealing head in order to properly seal the container.
In conventional systems, high currents are produced in the coil of the sealing head and, due to the relatively high resistance of the coil, results in the drastic elevation of the temperature of the coil and any surrounding structures. Therefore, the induction sealing units of the prior art employ hollow copper tubing when forming the coil in the sealing head to permit cooling water to flow through the hollow copper tube coil and cool the sealing head.
Unfortunately, the water cooling systems which cool the sealing heads (via hollow copper tubing coils) are expensive, bulky and inefficient. Indeed, such water cooling systems require water tubing, radiators, radiator fans, compressors and the like in order to adequately cool the system.
There exists a need for an induction heating unit which does not require expensive and bulky water cooling systems. Accordingly, it is an object of the present invention to provide an induction heating head which includes an slotted ferrite heating head. It is a further object of the present invention to provide an induction heating head which is more energy efficient.
In order to meet the objects of the invention as listed above and other objects, the present invention includes a housing, a plurality of ferrite cores disposed within the housing and a litz wire coil disposed adjacent the ferrite cores for producing an electromagnetic field. The cap sealing unit may also include a heat sink coupled to the housing, where at least some of the ferrite cores are bonded or operatively engaged to the heat sink for transferring heat thereto.